Electrical boxes are employed in a wide variety of applications as a means of providing a junction point for electrical wiring. Some common non-limiting applications of electrical boxes include switches, power receptacles, and fuse panels in building structures. Electrical boxes may also be used in a variety of other applications requiring junction points for electrical wiring such as automotive, aeronautical, and industrial applications, for example.
Generally, an electrical box is mounted in a desired location on a structure. Electrical wire is then routed throughout the structure to the electrical box. The electrical wire is typically passed through an aperture formed in an outer wall of the electrical box, where it is connected with an electrical device within the electrical box such as a switch, an outlet, or a fuse.
To facilitate the introduction of the electrical wire to the interior of the electrical box, the outer walls of electrical boxes typically contain at least one, and often several, of the apertures therein. These apertures vary in size and shape depending on the type of electrical box being used, but are typically larger in size than a cross-sectional area of the electrical wire being passed therethrough in order to allow easy insertion of the electrical wire. While oversized apertures are desirable as a means of maximizing installation efficiency, the oversized apertures also have the negative impact of leaving the interior of the electrical box exposed to the outside environment. This exposure allows air surrounding the electrical box to pass through the electrical box and enter into the building structure, thereby reducing thermal efficiency of the building structure. The oversized apertures also have the negative effect of permitting moisture and other contaminants to enter the electrical box, thereby accelerating the degradation of electrical connections within the electrical box or otherwise adversely affecting the electrical box.
Knockouts are one means of minimizing exposure of the interior of the electrical box to the outside environment. Knockouts are typically rigid obstructions within the aperture that can be removed or “knocked out” as needed to make additional apertures available for use. Knockouts are effective in preventing air, moisture, and contaminants from entering virgin apertures, but provide no protection once the knockout is removed and an electrical wire is inserted. Furthermore, the knockouts cannot be replaced if the electrical wire is removed from the electrical box at a later time because such knockouts are typically configured to be disposable as they do not include a means for being reinserted and secured within the apertures of the electrical box.
Another means of limiting exposure inside electrical boxes is to place a foam cover over the aperture. When an electrical wire is inserted into an aperture, an opening is formed in the foam cover similar in size to the cross section of the inserted electrical wire. The opening provides some protection from the outside environment so long as the electrical wire remains inserted in the electrical box, although due to the nature of the foam materials used, some leakage around the electrical wire does occur. However, upon removal of the electrical wire from the electrical box, the opening remains open, leaving the interior of the electrical box exposed to the exterior environment. Such foam covers also tend to rip easily, thereby creating additional pathways for air to enter the electrical box having the foam cover. Furthermore, due to the inelastic nature of foam, such foam covers tend to provide a loose fit that may also provide additional pathways between the electrical box and the foam cover for air to enter the electrical box.
In addition to undesired exposure to the environment, oversized apertures do not sufficiently secure inserted electrical wires within the box. Thus, once a wire is inserted through the oversized aperture, it must be held in place until being connected to the electrical device. This can be excessively cumbersome for a user as the user may have to secure a position of each of the electrical box, the wire, and electrical device relative to each other to more easily couple the wire to the electrical device.
One solution to this deficiency in the art has been the use of adjustable cable clamps installed in the oversized apertures. While effective, cable clamps can be cumbersome, requiring the clamp to be loosened and tightened whenever an electrical wire is inserted or removed. Cable clamps may also contribute to air entering the electrical box as such cable clamps often provide a rigid opening surrounding the wire that has a slightly larger cross-sectional area than the wire. Additionally, the cable clamp is an auxiliary apparatus that must be installed into each aperture as necessary.
Another solution to secure the electrical wire within the electrical box has been to include a clutching feature in the aperture. As the electrical wire is inserted through the aperture, the clutching feature opens inwardly, remaining in contact with the exterior of the electrical wire. When force is applied to remove the electrical wire from the electrical box, the clutching feature tightens against the electrical wire, preventing removal. While the clutching feature is effective in securing the electrical wire without auxiliary clamps, it prevents easy removal of the electrical wire when desired.
It is therefore desirable to produce a means for sealing peripheral apertures of an electrical box prior to and during insertion of an electrical wire, as well as after removal of the electrical wire, while removably securing the electrical wire within the aperture.